In augmentative communication, iconic systems have employed general keyboard configuration structures to promote learnability and selectability for both direct selection keyboards and keyboards activated using some type of scanning system (including those used by people who were physically unable to actuate a key directly, but did so through some type of switch mechanism) to reduce the number of keystrokes required to generate natural language words in both highly and lightly inflected natural languages. In these iconic systems, such as that discussed in U.S. Pat. No. 4,661,916 to Baker et al., incorporated herein by reference in its entirety, icons were substituted for characters on a keyboard to permit access of words and word phrases using a reduced number of keystrokes. Such iconic systems also permitted important reductions in the number of keys scanned to reach a desired index, especially for people who did not want to invest the time and effort necessary to learn iconic structures.
The use of polysemous, multi-meaning icons enabled developers to construct iconic sequences to reduce the number of keystrokes, scanning steps, and memory requirements for representing natural language. Thousands of words were able to be represented by sequences of polysemous icons. The efficiency of having thousands of words represented by short icon sequences was used in tens of thousands of augmentative communication devices worldwide. However, time had to be invested by the user and/or by a teacher to learn the many icon sequences necessary to access words.
Representing thousands of words through iconic sequences, however, was not the only way to use keyboards to represent language. Simpler keyboards, somewhat easier to use and master, were developed which included keys with single meaning icons and/or which included character keys. Single meaning icons and character keys permitted access to a single word, phrase or sentence via simple keystrokes and thus were easy to use. However, keyboards lacked the word range and the efficiency and flexibility of iconic sequences. Thus, a need exists to combine the ease of use of single meaning icon and character keys with the efficiency and flexibility of iconic sequences. Further, a need exists to combine the reduced scanning burden achieved by use of icon sequences in a predictive manner such as that discussed in U.S. Pat. No. 5,297,041 to Kushler et al., incorporated herein by reference in its entirety, with the ease of use of single meaning icon and character keys.